Through the process of extrusion, a vast array of products made from a vast array of materials can be manufactured to have a consistent cross section. To form an extrusion, material is pressed or drawn through a die of a predetermined profile. One material that is commonly extruded is aluminum. The aluminum is heated to approximately 500 degrees centigrade, softening the material. It is then run though the die and allowed to cool. The extrusion process produces an end product that can be cut to any desired length needed for the finished product, including being customized to the customer.
Extruded aluminum profiles have been used to house strips of light emitting diodes. The profiles may be mounted to a desired surface or recessed into channels formed on the mounting substrate. The extruded aluminum profiles form open channels in which the light emitting diode strips are inserted. The aluminum profiles then require a separate lens to be positioned to cover the open end of the profile's channel. Most often, these lenses are slid into the extrusion along the length thereof. The lenses have also been designed to snap into these aluminum extrusions without having to be slid along the length of the aluminum extrusion.
The inventors have determined a number of problems associated with the manufacture of LED fixtures having aluminum extruded profiles fitted with separate lenses. First, the slide-in lenses severely limit the ability to maintain the light fixtures. Most often, the extrusions are cut or selected to be substantially the same length as their supporting surface. As a result, impediments exist, such as the side walls of a cabinet, which would prevent the lens from being removed, without fully disengaging the extruded housing from the support surface.
Second, extruded aluminum does not possess the necessary light transmission properties to act as a lens for the fixture. Therefore alternative materials must be used, often times various polymers. The use of polymer for the lens, while the profile housing is made from aluminum, causes manufacturing issues. The material of the lens and the material of the housing portion have different levels of warp, different degrees of expansion and contraction/shrinkage when the extruded material is cooled. Often, the aluminum extrusion will be sourced to one supplier while the polymer extrusion is sourced to a second supplier. As a result, it can be difficult to provide the lenses and the housings with sufficiently similar dimensional tolerances. Therefore, the lenses will often be of insufficient size to properly couple with the housing. This leads to lenses which are either too large to be properly inserted or too small, having them fall into the channel of the aluminum extrusion. Even if the lens includes a lip portion to prevent falling into the channel, a lens that is too small will be unable to properly engage the inside of the channel.
Third, aluminum is being a more and more expensive material. This is especially true of aluminum products formed outside of the United States, because tariffs have been placed upon the importation of these products.
As a result of these problems, the inventors have created an improved extruded housing for strips of light emitting diodes (LEDs). The improved housing uses a single polymeric material for the entire housing, both a channel portion and a lens portion. The channel and lens portions are preferably formed of high density polyethylene polymer. The channel portion and the lens portion are co-extruded to provide a unitary housing where the lens portion is formed with the trough portion in a hinged relationship. This hinged connection, referred to as a “living hinge,” allows the lens to be removably coupled across the open side of the trough, providing selective access to the trough for installation or removable of an LED strip positioned therein. Preferably the co-extrusion of the housing includes a first pigment added to the lens portion to provide a diffusive translucent cover capable of emitting light. Preferably, the co-extrusion of the housing includes a second, different pigment added to the material forming the trough portion to form an opaque region, preferably similar in finish to aluminum.
These and other aspects of the present invention will become apparent to those skilled in the art after a reading of the following description of the preferred embodiments, when considered in conjunction with the drawings. It should be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention as claimed.